ㄴ 듯이 오르다

rise like crazy

-ㄴ 듯이 means 'as if, like', and in all four lines here the phrase is 미친 듯이 오르다, 'to go up like mad'. Every one is about a figure climbing steeply, as in 정말 미친듯이 오르면 1년에 10% 오르잖아. 미친 듯이 attaches to plenty of other verbs too, always meaning 'to an insane degree'; writing it as one word, 미친듯이, is common but not the standard spelling.

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